In what is clearly a moment of pride for the Indian Navy, Defence Minister Manohar Parrikar and Maharashtra Chief Minister Devendra Fadnavis on Monday undocked the first indigenously-built attack submarine Scorpene from Mumbai's Mazagon docks.

"While the launch would be a more significant event, the floating out of Scorpene will commence its sea trials, and more importantly, clear the dry dock that it presently occupies for the construction of the next one," a senior submariner told Zee News.

"After undergoing trial test run at sea to check technical glitches, if any, the sub will be commissioned on September 2016," an Indian Navy official told the Times of India.

Currently, the Indian Navy operates only 14 conventional diesel-electric submarines. 10 of them are ageing Russian Kilo class and four are German HDW class submarines.

The government is planning on getting 30 submarines before 2022, but some of the projects have been delayed. The original delivery schedule for the first submarine was December 2012 and remaining submarines were to be delivered at intervals of one year each.

The delivery schedule was delayed to get approval from the government for cost revisions.

According to ToI, the revised cost of the submarines has already overshot its original budget by almost Rs 5,000 crore. "The revised cost of the submarines is approximately at Rs 23,562 crore against the originally approved Rs 18,798 crore," a source told ToI.